In such processes, the dialkyl carbonate is converted into diaryl carbonate via the following steps. In a first step transesterification of the dialkyl carbonate with the aryl alcohol takes place to yield alkyl aryl carbonate and alkyl alcohol. In a second step disproportionation of the alkyl aryl carbonate takes place to yield diaryl carbonate and dialkyl carbonate. Further transesterification of the alkyl aryl carbonate with aryl alcohol yielding diaryl carbonate and alkyl alcohol may also take place.
WO200142187 discloses a process for preparing diphenyl carbonate from a dialkyl carbonate and phenol. In said process, use is made of 3 reactive distillation columns in series: see columns A, B1 and C in FIG. 2 of WO200142187. Said process is characterized in that the top stream from the third reactive distillation column C is recycled to the first reactive distillation column A.